Process for making high solids fabric softeners using low amounts of solvents and no side reactions

ABSTRACT

A process is disclosed for making substantially solvent free quaternary ammonium compounds using fatty acids, amines and quaternizing agents without side reactions that would produce esters of fatty acids. A relatively small amount of a water-alcohol solvent is used in the quaternizing reaction after which a fatty acid is added and the solvent removed by sparging and/or vacuum.

This application is a continuation of application Ser. No. 474,347,filed on Feb. 2, 1990, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a process for making substantially solvent freequaternary ammonium compounds using fatty acids, amines and quaternizingagents without side reactions such as those reactions that would produceesters of fatty acids. A more fluid product is obtained than theester-containing softener blends used for dryer softener sheets.Ordinarily quaternization of the amine takes place in the presence ofthe fatty acid and the quaternizing agent, resulting in the formation ofthe ester of the fatty acid which makes the resultant product viscousand difficult to handle. By employing the method of the presentinvention, in which a relatively small amount of a water-alcohol solventis used in the quaternizing reaction after which a fatty acid is addedand the solvent removed, a product is obtained which is ready to beflaked or powdered and can be used as a fabric softener, lubricant, hairconditioner, in the manufacture of aqueous dispersions and the like.

2. Brief Description of the Prior Art

The preparation of quaternary ammonium compounds is usually conducted instainless steel or glass-lined equipment to which a tertiary amine ischarged and a solvent. Flammable solvents such as isopropyl alcohol aregenerally used although mixtures of isopropyl alcohol and watersometimes are employed or water alone is used. Flammable solvents areundesirable because they are a fire hazard and special handlingprocedures are required when they are used. In many applications, thesesolvents have to be stripped from the mixture when the reaction iscompleted because the ultimate use of the product is in a solventless orsolid form.

After the reactants are loaded into the reactor they are heated to atemperature of about 50° to about 100° C. after which a quaternizingreagent is added. In some instances an exotherm is produced as a resultof the quaternizing reaction and the reactor and its contents have to becooled. The rate of addition of the quaternizing agent can also becontrolled in order to minimize or eliminate the exotherm. As notedpreviously, in some instances, the solvent, if any is employed in thequaternizing reaction is stripped from the quaternary ammonium compoundobtained since some commercial uses for the compounds are in solventlesssystems. Additionally, bulk shipments of quaternary ammonium compoundswith solvents adds to transportion costs which is another reason toremove the solvents.

It is also known in the prior art that when water alone is used as thesolvent a gelatinous sticky mass is obtained from which the water isdifficult to remove. When alcohol is used as the solvent for thequaternizing reaction the products obtained are not as difficult tohandle as when water is used, however, when used, it presents not only afire hazard but also an environmental problem if released to the air.The combinations of water and alcohol have been used for several yearsin quaternization reactions and this solvent mixture generally isremoved by either sparging and/or by applying a vacuum to the quaternaryammonium compound thus produced which contains the solvents. Theseprocesses, although commercially employed are not entirely satisfactoryprimarily because the mixture of solvents with the quaternary ammoniumcompound and other reactants and by-products is viscous to the pointwhere solvent removal can be difficult.

The largest use for quaternary ammonium compounds is as a fabricsoftener and presently accounts for more than about three quarters ofthe total market for these material. Some fabric softeners are suppliedas a liquid dispersion of from about 3% to about 10% by weight of thequaternary ammonium compound which is adapted to be added during therinse cycle of a commercial or home laundering operation. Anothersignificant fabric softening application is the utilization ofquaternary ammonium compounds in combination with a substrate such as anonwoven fabric or a polymeric foam such as a polyurethane foam, thissubstrate so treated being added to a fabric dryer such as a clothesdryer while the fabric or clothes are still damp. The quaternaryammonium compound is formulated usually with a fatty acid or ester whichpromotes the transfer of the quaternary ammonium compound from thenonwoven or porous polymeric substrate to the fabric or clothes.

Quaternary ammonium compounds are now being added to both solid andliquid laundry detergent compositions so that the quaternary ammoniumcompound can be incorporated as a fabric softener during the wash cycleof fabrics or clothes. The most successfully utilized quaternaryammonium compounds in this last respect are the dimethyl (dihydrogenatedtallow) ammonium chlorides or methyl sulfates. Other quaternary ammoniumcompounds such as imidazolines and amidoamine quaternaries are alsoused.

Quaternary ammonium compounds are also used to manufactureorganomodified clays which may be added to drilling muds utilized indrilling oil wells, the organomodified clay providing improvedlubrication and rheological properties of the drilling muds. Theseorganoclays are also employed as thixotropic agents in plastisols,organosols, paints and other protective coatings, grease additives,foundry additives, cosmetics, resins and printing inks. The most commonquaternary ammonium compounds employed in this regard aremethyldi(hydrogenated tallow) benzylammonium chloride,dimethyldi(hydrogenated tallow) ammonium chloride anddimethyl(hydrogenated tallow) benzylammonium chloride.

Quaternary ammonium compounds are also employed as disinfectants, e.g.bactericides or bacteristats, the most common of which is the quaternaryammonium compound of benzylchloride and a dimethylalkyl-amine, the alkylgroup having from about 12 to about 16 carbon atoms as well as trimethylalkyl ammonium chlorides where the alkyl group is a long chain alkylsuch as an octadecyl group. Additionally, dimethyldicoconut-oil fattyammonium chlorides are also effective bactericides especially againstanaerobic bacteria which are sulfate reducers that are found in oilwells, these bacteria causing severe corrosion problems and plugging offormations which this type of quaternary ammonium compound can minimizeor eliminate. Additionally, these quaternary ammonium compoundseffective against anaerobic bacteria are also effective in removing oilfrom sand stone formations in oil wells and provide a two-fold effect offunctioning not only as a bactericide but also in promoting so-calledsecondary recovery of oil.

An additional use of quaternary compounds is in hair treatment becauseof the antistatic effects obtained with such compounds, as well as theincreased wetting which promotes improvements in both wet and drycombing or brushing and improves luster and feel. The most commonly usedquaternary ammonium compounds in this respect are trimethylalkylammoniumchloride, pentaethoxystearylammonium chloride,dimethylstearylbenzylammonium chloride and dimethyldialkylammoniumchlorides.

It is therefore an object to overcome these and other difficultiesencountered in the prior art.

It is also an object of the present invention to provide a method formanufacturing a mixture of quaternary ammonium compounds with a fattyacid inter allia which can be used in fabric softening applications. Itis also an object of the present invention to provide such mixtures.

It is a further object of the present invention to provide a method formaking a mixture of a quaternary ammonium compound from which thesolvents such as mixtures of water and alcohol can be readily removed byconventional methods such as sparging and/or vacuum.

It is also an object of the present invention to provide such a mixturewhich is relatively fluid so that the removal of solvents such asmixtures of alcohols and water is readily achieved by sparging and/orvacuum.

It is also an object of the invention to provide such mixtures with lowamounts of solvents but are nonetheless relatively fluid so that thesolvents such as water and alcohol can be readily removed by spargingand/or vacuum.

It is also an object of the invention to provide a method for makingsuch mixtures for use as fabric softeners.

It is a further object of the present invention to provide a compositioncomprising such mixtures with low amounts of solvents such as water andalcohol that lend themselves to the easy removal of such solvents bysparging and/or vacuum.

It is a further object of the invention to provide mixtures ofquaternary ammonium compounds with a fatty acid that can be employed inany or all of the foregoing applications.

These and other objects have been achieved according to the presentinvention which will be further understood in view of the followingdescription and claims.

SUMMARY OF THE INVENTION

It has been found that a highly functional mixture of a quaternaryammonium compound, and a fatty acid can be obtained that issubstantially free of fatty acid esters, amine salts and solvents by aquaternization reaction in which an amine is quaternized by aquaternizing agent in the presence of relatively small amounts of waterand an alcohol until the quaternization reaction is substantiallycomplete. A first mixture of a quaternary ammonium compound, alcohol andwater is obtained after which a fatty acid is added to the first mixtureto obtain a second mixture that is relatively fluid. This is followed byremoving the alcohol and water as a vapor from the second mixture tothereby obtain a quaternary ammonium compound in combination with suchfatty acid, the combination being substantially free of fatty acidesters, amine salts and the water and alcohol.

The prior art method uses 3-5 wt % water and 2-3 wt % isopropanol tofacilitate pumping and transportation. The process according to theinvention uses less than 3% water and less than 2% alcohol (e.g.isopropanol). The fatty acid is added which thins the product wherebysolvents may be removed and the product remains fluid at lowertemperatures. This allows for lower storage temperatures thanquaternaries alone or with the solvent mixtures of the prior art andalso lower storage than quaternaries blended with the traditional estersused in the known prior art methods.

DETAILED DESCRIPTION

The tertiary amine employed according to the invention has the formula:##STR1## where R, R¹ and R² can be any of the following in combination

(1) linear or branched chain saturated or unsaturated hydrocarbon groupshaving up to about 22 carbon atoms;

(2) a lower hydroxy alkyl group;

(3) an alkyl amido alkylene group of the formula: ##STR2## where R⁴ islower alkylene and R³ is any of R, R¹ or R² ;

(4) lower alkoxy group;

(5) poly(oxyloweralkylene) group;

so that at least one of R, R¹ or R² is one of said linear or branchedchain aliphatic saturated or unsaturated hydrocarbon groups;

or said tertiary amine is an imidazoline of the formula: ##STR3## whereR⁵ is a linear or branched chain, aliphatic saturated or unsaturatedhydrocarbon group having up to about 22 carbon atoms and R⁶ is a loweralkylene group;

said quaternizing agent being known in the art and which will produce aquaternary ammonium compound having an anion A⁻. Generally these anionsare those having the formula R⁷.sub.(a-b) X;

where R⁷ is a lower alkyl group or cyclo lower alkyl group such asbenzyl, cyclohexylmethyl, tolyl, xylyl, naphthylmethyl, and X ischlorine, iodine, bromine, sulfate, methyl sulfate, carbonate,phosphate, borate group, where (a) is equal to the valence of X and (b)is from 1 to the valence of X and are based on quaternizing agentshaving the formula R⁷ _(a) X.

Examples of tertiary amines that can be employed include:

distearyl methyl amine,

dihydrogenated tallow methyl amine,

ditallow methyl amine,

dimethyl hydrogenated tallow amine,

dimethyl coco amine,

distearyl ethoxyethyl amine,

stearyl bis-hydroxyethyl amine,

stearyl bis (polyethoxy ethanol) amine,

bis (tallowamidoethyl) 2-hydroxyethyl amine,

bis (tallowamidoethyl) 2-hydroxylpropyl amine,

1-hydrogenated tallow amido ethyl -2-hydrogenated tallow imidazoline,

1-ethylene bis (2 tallow, 1 methyl, imidazolinium)

dimethyl amino propyl tallow amido-amine and

hydrogenated tallow hydroxyethyl imidazoline,

Examples of Quaternizing Agents that can be employed include:

dimethyl sulfate,

diethyl sulfate,

methyl chloride,

methyl bromide and

benzyl chloride.

Said fatty acid is a linear or branched chain aliphatic saturated orunsaturated fatty acid having from about 12 to about 22 carbon atomsbased on coconut oil, vegetable oils, seed oils, animal fats and fishoils;

The quaternary ammonium compound thus obtained has the formula: ##STR4##where A⁻ is an anion based on R⁷.sub.(a-b) X or equivalent anions knownin the quaternary ammonium compound art;

and the fatty acid ester has the formula: ##STR5## where R⁸ is a linearor a branched chain aliphatic saturated or unsaturated hydrocarbon grouphaving from about 11 to about 21 carbon atoms.

As used throughout this specification the terms lower alkoxy, loweralkylene and lower alkyl are intended to include compounds having up toabout 3 or about 4 carbon atoms including the various isomericconfigurations thereof e.g. t-butyl, i-butyl, i-propyl and the like andthe various mixtures thereof whether such mixtures of such groupscontain components having one, or two, or three or four carbon atoms ormore and also where such groups individually or in combination are inany of their isomeric forms.

Equivalent amines (including imidazolines), quaternizing agents, fattyacids and surface active agents are disclosed in U.S. patents toMarschner U.S. Pat. No. 4,859,456; Caswell et al., U.S. Pat. No.4,857,213; Demangeon et al., U.S Pat. No. 4,851,141 and Mermelstein etal., U.S. Pat. No. 4,844,824 all of which are incorporated herein byreference.

Sparging is generally conducted by passing an inert gas such asnitrogen, (carbon dioxide etc.)through the mixture. Combinations ofinert gases may also be used.

One or more valved gas inlets are placed in the reactor in which thequaternary ammonium compound is formed, the openings being below thelevel of the reactants in the reactor and preferably at the bottom ofthe reactor. Similarly, a pipe or a plurality of pipes can be insertedthrough the top of the reactor down to the reactants so that theopenings thereof are positioned below the surface of the reactantspreferably towards the bottom of the reactants and the reactor. Thesparging gas is then introduced at a sufficient flow and pressure sothat the sparging gas introduced into the reactants can sweep thereacting mixture and pull the water and alcohol from the reactants asthe gas exits the reactants at the surface in the form of bubbles.

The solvents may also be removed by vacuum, for example under reducedpressures of from less than 760 mm to about 2 mm of mercury andespecially from about 200 mm to about 10 mm of mercury either before,during or after sparging. Any combination or sequences of sparging andvacuum stripping of solvents may be employed.

The reactants in combination with the fatty acid, during sparging andvacuum treatment may be held at a temperature from about 50° to about120° C. and especially from about 80° to about 100° C.

The amine, water and alcohol are added to the reactor and heated toabout 140° F. prior to the addition of the quaternization reaction andpreferably a slight nitrogen purge is initiated at this time and priorto the addition of the quaternizing agent. In conducting the reaction,the amine is present in a slight stoichiometric excess e.g. from about0.005 to about 5% excess and especially from about 0.01 to about 1%excess and the quaternizing agent is added incrimentally so as tomaintain a reaction temperature of from about 50° to about 100° C. andespecially from about 60° to about 90° C. It is standard practice in theart to add the quaternizing agent incrementally since the quaternizationreaction is generally exothermic and the temperature of the reaction canbe controlled by this type of addition. The progress of the reaction isfollowed so that when the amount of free amine has stabilized at fromabout 1 to about 2% by weight (that point in the reaction when thequaternization reaction has been substantially completed) the fatty acidis added. After addition of the fatty acid, the mixture is heated toanywhere from about 80° to about 110° C. and especially from about 90°to about 100° C. and the solvents (water and alcohol) are removed eitherby sparging, vacuum stripping or any combination of the two processes inany order, combination or sequence of sparging and vacuum strippingsteps.

In conducting the quaternization reaction, sufficient alcohol is addedso that there is from about 0.1 to about 5% and especially from 1 toabout 3% by weight of alcohol present and water is similarly added sothat there is from about 0.25 to about 5% and especially from about 1 toabout 4% by weight of water present. The amount of water and alcohol interms of weight percent is calculated on the basis of amine,quaternizing agent, water, alcohol and fatty acid in the reactionmixture. The alcohol is a lower alkanol such as those alcohols having upto about five carbon atoms, especially the mono-hydroxy alcohols andincludes the various isomers thereof such as isopropyl alcohol, isobutylalcohol, t-butyl alcohol and various combinations thereof includingazeotropes of such alcohols or such alcohols and water.

The amount of quaternary ammonium compound and fatty acid obtained inthe mixture after the solvents have been removed from the reaction arefrom about 10 to about 90 weight percent and especially from about 55 toabout 75 weight percent of quaternary ammonium compound and from about90 to about 10 weight percent and especially from about 25 to about 45weight percent by weight of fatty acid. The amine and quaternizing agentare reacted in sufficient ratios and the fatty acid is added afterwardsto the quaternary ammonium compound thus obtained in sufficient amountsso as to obtain the foregoing ratios after the water and alcohol havebeen removed.

The alcohol and water are sufficiently removed from the quaternaryammonium compound mixed with the fatty acid so that a mixture ofquaternary ammonium compound and fatty acid is obtained in amounts fromabout 95% to about 100% and especially about 98% to about 100% i.e.substantially all of the water and alcohol solvents are removed. Statedotherwise the mixture may contain anywhere from about 2% to about 5% ofthe water and alcohol solvent down to that point where substantially allor all of the water and alcohol solvent is removed.

In one embodiment, the method of the invention is preferably practicedso that the quaternary ammonium compound that is obtained has thestructural formula (I) wherein at least one of R, R¹ and R² is abranched chain or linear aliphatic saturated or unsaturated hydrocarbongroup having from about 12 to about 22 carbon atoms, preferablysaturated, and especially those based on hard tallow acids (i.e.hydrogenated tallow fatty acids) and the balance, if any of theaforesaid R, R¹ and R² groups is a lower alkyl group and R⁷ is a loweralkyl group. In another embodiment X is a sulfate group.

The invention also relates to a mixture of the various quaternaryammonium compounds as described above in combination with the fattyacids in the amounts and ratios as described previously.

The invention also relates to a fabric softening article of manufacturecomprising a fabric softening amount of any of the mixtures as describedherein operatively associated with a substrate that will release suchmixture to a fabric under fabric softening conditions encountered in afabric or clothes dryer and includes the use of any of the aforesaidmixtures in a fabric softening relationship with a nonwoven or wovenfiber or a polymeric open-celled or substantially open-celled foamsubstrate, such combination being prepared in a manner well known in theart. The mixture is employed in an amount from about 0.1 to about 10 gmson a 9"×11" sheet and especially about 1 to about 3 gms on a 9"×11"sheet.

The various polymeric foams that are employed in this respect comprisepolyurethane foams as well as any of the art known equivalent foams.

Additionally, the invention is directed to a fabric cleaning compositioncomprising a detergent in combination with a fabric softening amount ofany of the mixtures described herein. These detergents can be any of theart known anionic, cationic, nonionic or amphoteric synthetic detergentsor wetting agents that are well known in the art or a soap i.e. thereaction product of a fatty acid with a alkaline hydroxide that is watersoluble e.g. fatty acid reaction products of sodium, potassium orammonium hydroxides or amines or the art known equivalents thereof.

Shampoos may also be formulated according to the invention with suchdetergents and a hair conditioning amount of the quaternary ammoniumcompound and fatty acid mixtures of the present invention.

These surfactants are further described in Kirk-Othmer, Encyclopedia ofChemical Technology, 3rd Edition Vol. 22 pp. 332-432 which isincorporated herein by reference. Some specific detergents that areespecially suitable in this regard include:

alkyl benzene sulfate,

sodium lauryl ether sulfate,

nonyl phenyl ethoxylates and

alkyl alcohol ethoxylates.

The mixture of the invention is incorporated into the detergents orsoaps (whether solid or liquid) by blending in a manner well known inthe art. The amount of the mixture employed is any where from about 1 toabout 50 and especially from about 2 to about 30 wt. % based on thequaternary ammonium compound and the active components of the detergentor soap i.e. the component of the detergent or soap that has bothorganophilic and hydrophilic groups.

The following example is illustrative.

The method of the invention as well as a mixture obtained according tothis method is examplified by the preparation of a mixture employing thefollowing components in the indicated amounts.

    ______________________________________                                        Components       M.W.    Moles     % by Wt.                                   ______________________________________                                        Dihydrogenated Tallow-                                                                         523     1.00      53.52                                      Methyl-Amine                                                                  Dimethyl Sulfate 126     0.98      12.98                                      Water                              3.0                                        Ethanol                            2.0                                        Stearic Acid                       28.5                                       ______________________________________                                    

The amine, water and alcohol are charged to a reactor and heated to 140°F. A nitrogen purge was used over the surface of the reactants in thereactor to minimize contact of the reactants with air. Thedimethylsulfate was charged at a rate to maintain the temperature of thereactants at 140°-180° F. When the percentage of free amine hasstabilized at 1.0-2.0 weight percent the stearic acid is added andmixed. The mixture thus obtained is heated to 200° F. after which thewater and ethanol are removed by means of nitrogen sparging and/orvacuum stripping.

The foregoing method produced a reaction mixture which was analyzed byNMR analysis showing that it had the following components:

    ______________________________________                                                           Weight Percent                                             ______________________________________                                        Quaternary Ammonium compound                                                                       67                                                       Fatty Acid           33                                                       ______________________________________                                    

Although the invention has been described by reference to someembodiments, it is not intended that the novel method or the mixtureobtained thereby as well as the fabric softening article of manufactureand the detergent containing a fabric softening amount of the mixture belimited thereby but that certain embodiments are intended being includedas falling within the broad scope and spirit of the foregoing disclosureand the following claims.

I claim:
 1. A method for making a mixture of a quaternary ammoniumcompound and a fatty acid which is substantially free of solvents, fattyacid esters and amine salts by reacting a tertiary amine and aquaternizing agent in the presence of a solvent based on an alcohol andwater to obtain a first mixture of a quaternary ammonium compound, saidalcohol and said water, adding a fatty acid to said first mixture toobtain a second mixture that is relatively fluid and removing saidalcohol and said water as a vapor to thereby obtain said quaternaryammonium compound and said fatty acid that is substantially free ofsolvents, fatty acid esters and amine salts:where in said quaternizingreaction said amine is present in a slight stoichiometric excess basedon said quaternizing agent, said alcohol is present in an amount fromabout 0.1 to about 5% by weight, said water is present in an amount fromabout 0.25 to about 5% by weight, said amounts of alcohol and waterbeing based on the total amount of amine, quaternizing agent, alcohol,water and fatty acid; said tertiary amine having the formula: ##STR6##wherein R, R¹ or R² are: (1) a linear or branched chain aliphaticsaturated or unsaturated hydrocarbon group having up to about 22 carbonatoms; (2) a hydroxy lower alkyl group; (3) an alkyl amide alkylenegroup of the formula; ##STR7## where R⁴ is lower alkylene and wherein R³is (1), (2), (4), or (5); (4) a lower alkoxy group; (5) apoly(oxyloweralkylene) group; so that at least one of R, R¹, R² is oneof said hydrocarbon groups or one of said hydroxy lower alkyl groups; orsaid tertiary amine is an imidazoline of the formula; ##STR8## whereinR⁵ is a linear or branched chain aliphatic saturated or unsaturatedhydrocarbon group having up to about 22 carbon atoms and R⁶ is a loweralkylene group; said quaternizing agent being capable of producing aquaternary ammonium compound having anions A⁻ ; wherein said fatty acidis a linear or branched chain saturated or unsaturated fatty acid havingfrom about 12 to about 22 carbon atoms; said quaternary ammoniumcompound having the formula: ##STR9##
 2. The method of claim 1 wheresaid second mixture is subjected to sparging with a gas at temperaturesof from about 80° C. to about 100° C. to remove any of said water oralcohol.
 3. The method of claim 1 where said second mixture is subjectedto a vacuum to remove any of said water or alcohol.
 4. The method ofclaim 2 where said second mixture, is also subjected to a vacuum toremove any of said water or said alcohol.
 5. The method of claim 4 wheresaid quaternary ammonium compound is (I) and wherein at least one ofsaid R, R¹ and R² groups is a branched chain or linear, aliphaticsaturated or unsaturated hydrocarbon group having from about 12 to about22 carbon atoms and the balance, if any, of said R, R¹ and R² groups isa lower alkyl group.
 6. The method of claim 4 where said amine is adihydrogenated tallow methyl amine and said quaternizing agent is adialkyl sulfate and said fatty acid is stearic acid.
 7. The method ofmaking a fabric softening article of manufacture comprising making amixture of a quaternary ammonium compound and a fatty acid according tothe method of claim 4, and operatively associating a fabric softeningamount of said mixture with a fabric under fabric softening conditions.8. The method of claim 7 where said substrate is a non-woven fabric. 9.The method of claim 8 where said substrate is a polymeric foam.